Innovative size reduction of biomass reduces energy use, increases ease of bulk handling, increases density, reduces transportation costs, and facilitates efficient separation. One project aim is to develop new shear-dominant size reduction systems. UT studies indicate shear stresses were one-fifth tensile stresses to fail individual stems of switchgrass. Tensile failure stress increased two-fold as elapsed time increased from 2 to 386 h. Shear failure was insensitive to elapsed time after harvest. Size reduction metrics include energy per unit mass and particle size, shape, and density. Tasks include categorized listing of grinding units based on functional analyses, power, and grinding performance; systematic measures of biomass shear/tensile properties and failure characteristics; development of two to three innovative concepts as table-top proof-of-concept devices; and development of a new demonstration size reduction unit that most nearly meets performance criteria established early in the project.